Historically, advances in non-invasive diagnostic techniques such as echocardiography, computed tomography, and magnetic resonance imaging (“MRI”) significantly reduced the use of diagnostic endomyocardial biopsy (“EMB”) in practice. Despite this however, EMB remains a necessary diagnostic procedure because specific myocardial disorders that have unique prognoses and treatment are difficult to diagnose by noninvasive methods. Further, recent advantages in molecular biology and biomedical markers have once again increased the need of EMB. Specifically, analysis of a myocardial biopsy specimen may provide essential information on cardiac pathogensis. (Pawlak, Walczak et al. 2005)
Indications for endomyocardial biopsy may include unexplained cardiomyopathy, myocarditis, ventricular arrhythmias, cardiac hemachromatosis, amyloidosis, anthracycline cardiotoxicity, cardiac sarcoidosis, giant cell myocarditis, hypereosinophilic syndrome, or endocardial fibroelastosis. (Kilo, Laufer et al. 2006) EMB is also often used to evaluate the efficacy of immunosuppressive therapy after cardiac transplantation. (Kilo, Laufer et al. 2006) Finally, EMB may provide insight in the setting of unexplained, new-onset heart failure associated with a normal-sized or dilated left ventricle in addition to hemodynamic compromise. (Cooper, Baughman et al. 2007) Further, EMB may also be employed in the event of a suspected cardiac tumor. In fact, the performance of a EMB is recommended in the event (1) the diagnosis of a cardiac tumor cannot be established by noninvasive modalities (such as cardiac MRI) or less invasive biopsy; (2) tissue diagnosis can be expected to influence the course of therapy; (3) the chances of successful biopsy are believed to be reasonably high; and (4) the procedure is performed by an experienced operator. (Cooper, Baughman et al. 2007) The first nonsurgical techniques for cardiac biopsies were reported in 1958. In the 1960s, the safety of cardiac biopsy improved with sampling of the right interventricular septum, and designation of the heart borders by right heart catheterization before biopsy. While biopsy tissue samples had historically been obtained using cutting techniques, Sakakibara and Konno (Sakakibara and Konno 1962) introduced the use of a flexible bioptome that a biopsy sample to be obtained through a pinching technique. Some time thereafter, Caves et al (Caves, Stinson et al. 1973) modified the Konno biopsy forceps (Stanford Caves-Shulz bioptome) to allow percutaneous biopsies through the right internal jugular vein with only local anesthesia and rapid tissue removal. The reusable Stanford-Caves bioptome became the standard device for EMB for approximately 2 decades. (Cooper, Baughman et al. 2007)
The femoral artery may be used as a percutaneous access site for left ventricular biopsy. The right internal jugular vein is the most common percutaneous access site for right ventricular EMB in the United States. In Germany and Italy, the femoral vein is commonly used for percutaneous access. (Cooper, Baughman et al. 2007) EMB is usually performed safely under fluoroscopic guidance. Some operators use fluoroscopy and echocardiography in combination to enhance entry into the right ventricle.
EMB is a very safe procedure and procedural mortality ranges from 0-0.4%. A number of potential complications are inherent, however, in the operation including: Perforation/pericardial tamponade (Incidence: 0-0.5%), Tricuspid valve damage (14%), Bleeding at puncture site (venous/arterial due to accidental arterial puncture) (0.14-0.4%); Pneumothorax (0.1%), Arrhythmias (supraventricular/ventricular tachycardia/complete heart block) (0.25-1.1%). Overall, complications are infrequent for skilled surgeons, and especially life-threatening complications are rarely encountered. (Kilo, Laufer et al. 2006)
The risks of EMB may be divided into those that are acute and those that are delayed. Immediate risks of biopsy include perforation with pericardial tamponade, ventricular or supraventricular arrhythmias, heart block, pneumothorax, puncture of central arteries, pulmonary embolization, nerve paresis, venous hematoma, damage to the tricuspid valve, and creation of arterial venous fistula within the heart. The risks of EMB vary with the experience of the operator, clinical status of the patient, presence or absence of left bundle-branch block, access site, and possibly bioptome. Delayed complications include access site bleeding, damage to the tricuspid valve, pericardial tamponade, and deep venous thrombosis. (Cooper, Baughman et al. 2007)
Clearly, there is a need for myocardial biopsy including the epicardial tissue that is easy to use, relatively inexpensive, and safe.